In poetry, the rhyme scheme refers to the pattern of repetition of sounds at the end of verses. Additionally, the rhyme scheme can be identified by marking verses with the same final sound using the same letter which is assigned from A to Z. In the case of the lines presented there is rhyme between the first and second line as the words "we" and "thee" have the same vowel sound and therefore they both will be marked with an A. Also there is rhyme between the third and fourth verse in "man" and "can" and this would be marked using the letter B. This means, the rhyme scheme is A, A, B, B as the first and second verse rhyme and the third and fourth rhyme.
